1. Field of the Invention
This invention relates to a gill structure for extracting oxygen from fluids in which oxygen is dissolved.
2. Description of Related Art
Copending U.S. patent application Serial No. 653,850, filed on Sept. 24, 1984, now U.S. Pat. No. 4,602,987 and assigned to the same assignee as the present application, discloses a system and process for the extraction of oxygen from fluids in which oxygen is dissolved. This copending application is hereby incorporated by reference. The copending application discloses a process in which oxygen is extracted from an oxygen bearing fluid by contacting the oxygen bearing fluid with a gill structure including a first surface of an oxygen permeable membrane, which can be in the form of a tube. A series of such tubes contain a carrier fluid having a binding-state oxygen carrier, called a heme, as a result of which oxygen which diffuses through membrane binds to the heme. The oxygen carrying carrier fluid is caused to flow to an electrode compartment of an electrochemical cell at which point the heme is electrochemically modified to release oxygen which can be removed for further use. The carrier fluid and heme can then be recirculated to the membranes.
Such extracted oxygen is useful in a variety of environments. For example, it may be used in a gasoline-spark ignition engine of an underwater vehicle to propel the vehicle through the water. An example of such a vehicle is schemically illustrated in FIG. 11 of said copending U.S. patent application Ser. No. 653,850. FIG. 11 of said copending application illustrates a 10 kilowatt engine driving a pair of gear driven thrusters and deriving power from a liquid fuel in a flexible bag, as well as oxygen extracted from a pair of gill structures which are schematically shown.
In the design of submerged vessels, minimizing drag is critical for the efficient operation of the vehicle. It is therefore desirable to minimize both the size of the gill structure and the amount of drag on the gill structure. However, the gill structure must also be designed for maximum oxygen extraction efficiency in order that sufficient oxygen can be supplied to the engine with a minimum sized gill structure. These are conflicting constraints.